1. Field of the Invention
The present invention relates to boat propelling systems, and more specifically, to a boat propelling system including an electric motor arranged to pivot a propelling system main body in a right-left direction with respect to the hull.
2. Description of the Related Art
As disclosed in JP-A 2006-199189, for example, use of an electric motor to pivot an outboard engine (propelling system main body) in a right-left direction with respect to a hull for steering the hull is a conventional technique.
According to the technique in JP-A 2006-199189, a target pivot angle of a propelling system main body (e.g., outboard engine main body) which pivots with respect to the hull, is set by using a steering wheel turning angle or the like. Then, based on an angle difference between an actual pivot angle and the target pivot angle of the outboard engine, a drive amount of an electric motor is determined and the electric motor is driven. The driving power of the electric motor is transmitted via a reduction gear mechanism to a shaft section, and as the shaft section rotates, the outboard engine is pivoted in a right-left direction with respect to the hull.
However, the reduction gear mechanism will lose operation accuracy due to deterioration from wear or the like. Then, even if the electric motor is driven by the drive amount which is based on the angle difference between the actual pivot angle and the target pivot angle, the actual pivot angle after the electric motor is driven is different from the target pivot angle. JP-A 2006-199189 makes no consideration of or compensation for a potential decrease in operation accuracy caused by deterioration or the like of the reduction gear mechanism which serves as a transmission mechanism, and therefore makes no disclosure or indication regarding determination of operation accuracy of the reduction gear mechanism.